1 K8S两种服务暴露方法
前面通过coredns在k8s集群内部做了serviceNAME和serviceIP之间的自动映射,使得不需要记录service的IP地址,只需要通过serviceNAME就能访问POD
但是在K8S集群外部,显然是不能通过serviceNAME或serviceIP来解析服务的
要在K8S集群外部来访问集群内部的资源,需要用到服务暴露功能
1.1 K8S常用的两种服务暴露方法
- 使用NodePort型的Service
nodeport型的service原理相当于端口映射，将容器内的端口映射到宿主机上的某个端口。
K8S集群不能使用ipvs的方式调度,必须使用iptables,且只支持rr模式 - 使用Ingress资源
Ingress是K8S API标准资源之一,也是核心资源
是一组基于域名和URL路径的规则,把用户的请求转发至指定的service资源
可以将集群外部的请求流量,转发至集群内部,从而实现'服务暴露'
1.2 Ingress控制器是什么
可以理解为一个简化版本的nginx
Ingress控制器是能够为Ingress资源健康某套接字,然后根据ingress规则匹配机制路由调度流量的一个组件
只能工作在七层网络下，建议暴露http, https可以使用前端nginx来做证书方面的卸载
我们使用的ingress控制器为Traefik
traefik：GITHUB官方地址
2 部署traefik
同样的,现在7.200完成docker镜像拉取和配置清单创建,然后再到任意master节点执行配置清单
2.1 准备docker镜像
docker pull traefik:v1.7.2-alpine docker tag traefik:v1.7.2-alpine harbor.zq.com/public/traefik:v1.7.2 docker push harbor.zq.com/public/traefik:v1.7.2
2.2 创建资源清单
mkdir -p /data/k8s-yaml/traefik
2.2.1 rbac授权清单
cat >/data/k8s-yaml/traefik/rbac.yaml <<EOF apiVersion: v1 kind: ServiceAccount metadata: name: traefik-ingress-controller namespace: kube-system --- apiVersion: rbac.authorization.k8s.io/v1beta1 kind: ClusterRole metadata: name: traefik-ingress-controller rules: - apiGroups: - "" resources: - services - endpoints - secrets verbs: - get - list - watch - apiGroups: - extensions resources: - ingresses verbs: - get - list - watch --- kind: ClusterRoleBinding apiVersion: rbac.authorization.k8s.io/v1beta1 metadata: name: traefik-ingress-controller roleRef: apiGroup: rbac.authorization.k8s.io kind: ClusterRole name: traefik-ingress-controller subjects: - kind: ServiceAccount name: traefik-ingress-controller namespace: kube-system EOF
2.2.2 delepoly资源清单
cat >/data/k8s-yaml/traefik/ds.yaml <<EOF apiVersion: extensions/v1beta1 kind: DaemonSet metadata: name: traefik-ingress namespace: kube-system labels: k8s-app: traefik-ingress spec: template: metadata: labels: k8s-app: traefik-ingress name: traefik-ingress spec: serviceAccountName: traefik-ingress-controller terminationGracePeriodSeconds: 60 containers: - image: harbor.zq.com/public/traefik:v1.7.2 name: traefik-ingress ports: - name: controller containerPort: 80 hostPort: 81 - name: admin-web containerPort: 8080 securityContext: capabilities: drop: - ALL add: - NET_BIND_SERVICE args: - --api - --kubernetes - --logLevel=INFO - --insecureskipverify=true - --kubernetes.endpoint=https://10.4.7.10:7443 - --accesslog - --accesslog.filepath=/var/log/traefik_access.log - --traefiklog - --traefiklog.filepath=/var/log/traefik.log - --metrics.prometheus EOF
2.2.3 service清单
cat >/data/k8s-yaml/traefik/svc.yaml <<EOF kind: Service apiVersion: v1 metadata: name: traefik-ingress-service namespace: kube-system spec: selector: k8s-app: traefik-ingress ports: - protocol: TCP port: 80 name: controller - protocol: TCP port: 8080 name: admin-web EOF
2.2.4 ingress清单
cat >/data/k8s-yaml/traefik/ingress.yaml <<EOF apiVersion: extensions/v1beta1 kind: Ingress metadata: name: traefik-web-ui namespace: kube-system annotations: kubernetes.io/ingress.class: traefik spec: rules: - host: traefik.zq.com http: paths: - path: / backend: serviceName: traefik-ingress-service servicePort: 8080 EOF
2.3 创建资源
2.3.1 任意节点上创建资源
kubectl create -f http://k8s-yaml.zq.com/traefik/rbac.yaml kubectl create -f http://k8s-yaml.zq.com/traefik/ds.yaml kubectl create -f http://k8s-yaml.zq.com/traefik/svc.yaml kubectl create -f http://k8s-yaml.zq.com/traefik/ingress.yaml
2.3.2 在前端nginx上做反向代理
在7.11和7.12上,都做反向代理,将泛域名的解析都转发到traefik上去
cat >/etc/nginx/conf.d/zq.com.conf <<'EOF' upstream default_backend_traefik { server 10.4.7.21:81 max_fails=3 fail_timeout=10s; server 10.4.7.22:81 max_fails=3 fail_timeout=10s; } server { server_name *.zq.com; location / { proxy_pass http://default_backend_traefik; proxy_set_header Host $http_host; proxy_set_header x-forwarded-for $proxy_add_x_forwarded_for; } } EOF # 重启nginx服务 nginx -t nginx -s reload
2.3.3 在bind9中添加域名解析
需要将traefik 服务的解析记录添加的DNS解析中,注意是绑定到VIP上
vi /var/named/zq.com.zone ........ traefik A 10.4.7.10
注意前滚serial编号
重启named服务
systemctl restart named #dig验证解析结果 [root@hdss7-11 ~]# dig -t A traefik.zq.com +short 10.4.7.10
2.3.4 在集群外访问验证
在集群外,访问http://traefik.zq.com,如果能正常显示web页面.说明我们已经暴露服务成功
